Add `-check-config` parameter in command-line

[martianzhang]

Please search the existing issues for relevant feature requests, add upvotes to pre-existing requests.

Feature Description

If the configuration file has some error, soar will bypass it and use the default value. Error messages were written in the log file. Add a new parameter for checking configuration may let the developer debug its config easier.

Use Case(s)

soar -check-config
soar -config test.yaml -check-config

[martianzhang]

• OnlineDSN test connection; If the -verbose flag is sepcified also report MySQL version.
• TestDSN test connection; If the -verbose flag is specified also report MySQL version.
• YAML marshal error check
• blacklist file exist check and regexp check